package algorithm.problems.array;

import java.util.HashSet;
import java.util.Set;

/**
 * Created by pradhang on 3/28/2017.
 * Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
 * <p>
 * click to show follow up.
 * <p>
 * Follow up:
 * Did you use extra space?
 * A straight forward solution using O(mn) space is probably a bad idea.
 * A simple improvement uses O(m + n) space, but still not the best solution.
 * Could you devise a constant space solution?
 */
public class SetMatrixZeroes {
    /**
     * Main method
     *
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        int[][] matrix = {{0, 8, 7}, {9, 0, 8}, {9, 9, 0}};

        new SetMatrixZeroes().setZeroes(matrix);
    }

    public void setZeroes(int[][] matrix) {
        Set<Integer> row = new HashSet<>();
        Set<Integer> col = new HashSet<>();
        int m = matrix.length;
        int n = matrix[0].length;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (matrix[i][j] == 0) {
                    row.add(i);
                    col.add(j);
                }
            }
        }

        for (int r : row) {
            for (int j = 0; j < n; j++) {
                matrix[r][j] = 0;
            }
        }

        for (int c : col) {
            for (int i = 0; i < m; i++) {
                matrix[i][c] = 0;
            }
        }
    }
}
